The present invention relates to a shaft sealing device and, more particularly, to a shaft sealing device with a dual sealing structure.
U.S. Pat. No. 6,935,633 issued Aug. 30, 2005 discloses a shaft sealing device including a sleeve, a flange, a seat ring, a compression ring, and a retaining ring. The sleeve is mounted on a rotary shaft of a machine and provided with an outer flange and a rotary ring mounted thereto. The flange is mounted on the machine and has an axial hole for supporting the sleeve that is rotatably extended therethrough. The flange further has a plurality of passages extending from the axial hole through an outer peripheral surface thereof for supplying and cycling fluid such as coolant. Thus, coolant can be fed into the axial hole via the passages for lubricating purposes. The seat ring is mounted in the axial hole of the flange and abuts against the rotary ring. The compression ring is fixed in the axial hole of the flange and includes a plurality of positioning holes and a plurality of tangent grooves. A flexible member is received in each positioning hole. The retaining ring is mounted around the sleeve and located between the seat ring and the compression ring. A plurality of engaging members are formed on a side of the retaining ring and engaged in the tangent grooves of the compression ring. The retaining member biased by the flexible members can only move in the axial direction and can not rotate. Thus, the retaining member presses the seat ring against the rotary ring, providing frictional contact between the seat ring and the rotary ring and, thus, providing enhanced sealing effect. However, the shaft sealing device of U.S. Pat. No. 6,935,633 is of a single-sealing type that is still less efficient in sealing effect than a dual-sealing structure more commonly utilized.
U.S. Patent Application Publication No. 2007/0246891 A1 discloses a shaft-sealing device including a shaft-mounting seat, a shaft-supporting mechanism, and a liquid guiding member. The shaft-mounting seat is mounted on a machine and includes a shaft bore for rotatably receiving a rotary shaft thereof. The shaft-mounting seat further includes a coolant inlet and a coolant outlet. Two seat rings are mounted in the shaft bore. The shaft-supporting mechanism includes a sealing-ring positioning assembly, two pushing members, a sleeve body, first and second rotatable sealing rings, and a sleeve-mounting member. The shaft-supporting mechanism is mounted around the rotary shaft for sealing purposes, with coolant flowing through the coolant inlet and the coolant outlet for lubricating purposes. The shaft-sealing device of U.S. Patent Application Publication No. 2007/0246891 A1 is of a dual-sealing type that provides more reliable sealing effect than a single sealing type. However, the friction between the seat rings and the first and second rotatable sealing rings is insufficient, since there is no mutual coupling arrangement therebetween.
A need exists for a shaft sealing device of a dual-sealing type to provide a reliable sealing effect.